Railway hopper cars transport and sometimes store bulk materials. Hopper cars generally include one or more hoppers which may hold cargo or lading during shipment. Hopper cars are frequently used to transport coal, sand, metal ores, aggregates, grain and any other type of lading which may be satisfactorily discharged through openings formed in one or more hoppers. Discharge openings are typically provided at or near the bottom of each hopper to rapidly discharge cargo. A variety of door assemblies or gate assemblies along with various operating mechanisms have been used to open and close discharge openings associated with railway hopper cars.
Transversely oriented discharge openings and gates are frequently coupled with a common linkage operated by an air cylinder. The air cylinder is typically mounted in the same orientation as the operating gate linkage which is often a longitudinal direction relative to the associated hopper.
Longitudinally oriented discharge openings and associated doors may provide a quicker discharge than transverse gates. Longitudinally oriented discharge openings and doors are often used in pairs that may be rotated or pivoted relative to the center sill or side sills of a hopper car. Longitudinally oriented discharge openings and doors may be coupled via linkages with a beam operated by an air cylinder. The air cylinder is typically mounted in the same orientation as the operating beam which is often a longitudinal direction relative to the associated hopper. The operating beam may be coupled to the discharge doors by door struts (linkages) that push (or pull) the gates open or pull (or push) them closed as the air cylinder moves the operating beam back and forth.
A hopper car is an example of a rapid discharge railcar. In general, rapid discharge railcars may use air cylinders, operating beams, and linkages to operate the bottom outlet doors.